It is generally known to provide scissor action tools, such as hedge shears, with a mechanism for absorbing the shock created by the impact of the tool handles upon completion of the scissor action, i.e., upon complete closure of the tool. Such a feature is particularly useful in hedge shears in light of the fact that a user typically tends to apply uniform scissor action to the tool even though the force required to trim hedges, limbs, etc., may vary depending upon the resistance presented by the growth. A shock absorbing feature therefore renders the use of the hedge shears more comfortable, reducing jarring and forearm fatigue.
Shock absorbing features presently provided on such cutting implements typically include spring biased mechanisms. Examples of such mechanisms are described in U.S. Pat. No. 2,727,304, issued Dec. 20, 1955 to Kulbersh; U.S. Pat. No. 1,822,591, issued Sep. 8, 1931 to Hickok; and U.S. Pat. No. 547,101, issued Oct. 1, 1895 to Williams. As more particularly disclosed in these patents, the shock absorbing feature comprises a spring biased plunger received in a cavity secured to one of the elongated members, while the other elongated member is provided with an abutting surface engageable with the plunger upon closure of the members.
Other ways to eliminate those objectionable impact shocks are disclosed in U.S. Pat. No. 2,105,332, issued Jan. 11, 1938 to Rauh and in U.S. Pat. Nos. 4,073,059, and 4,156,311, issued Feb. 14, 1978, and May 29, 1979, respectively, both to Wallace et al. Rauh discloses a shock absorber for garden shears comprising a pair of substantially U-shaped sheet metal shields configured to receive elongated blocks of rubber which are substantially enclosed within the shields. A pair of elongated holes is formed in the shield to permit lateral displacement of the shields when the rubber is fully compressed upon complete closure of the handles. The Wallace patents disclose the use of a power element or bumper in connection with a hand tool having a channel-shaped upper handle. The bumper, which is received within a pair of upstanding side walls, is formed of rubber or similar elastomeric material which will deform under the impact of the handles.
The present inventors have found, however, that shock absorbing mechanisms of the kind described in these prior art patents have various limitations. For example, and as also illustrated in the Wallace.RTM. 1994 Catalog at page 6, these mechanisms typically consist of a number of components which may require separate subassembly operations and can therefore be more costly to manufacture. In addition, the metal components of certain prior art mechanisms may rust if used in a humid environment, and for those using a rubber-like shock absorbing material, such material may become brittle with time. Accordingly, those prior art shock absorbing stops in addition to potentially being more costly to manufacture may also be less durable than simpler structures, thereby limiting the life expectancy of the tool or restricting desirable uses of the tool. Furthermore, elastomeric shock absorbers of the type disclosed in Rauh and the two Wallace patents suffer from the fact that to attempt to control the shock absorbing function, guiding plates or walls are required.
Thus, there continues to exist a need for an inexpensive shock absorbing mechanism or "bumper" for items such as hedge shears or the like which can alleviate the problems associated with conventional shock absorbing mechanisms, i.e., which is of simpler construction while permitting a certain amount of control over the performance of the bumper, which is of improved durability, and which facilitates assembly to the tool or replacement during the life of the hedge shears.